Network


Latest external collaboration on country level. Dive into details by clicking on the dots.

Hotspot


Dive into the research topics where Michael Lass is active.

Publication


Featured researches published by Michael Lass.


European Journal of Cardio-Thoracic Surgery | 1995

Aprotinin in elective primary bypass surgery. Graft patency and clinical efficacy.

Michael Lass; Welz A; Mathias Kochs; Mayer G; Schwandt M; Andreas Hannekum

The proteinase inhibitor aprotinin is used in open heart surgery to reduce intraoperative and postoperative blood loss and transfusion requirements. To investigate a possible influence on graft patency, a randomized double-blind group comparison study was carried out in male patients elected for primary bypass surgery. One hundred ten (55/55) patients received either placebo treatment or aprotinin according to the Hammersmith scheme (2 Mio KIU as loading dose before sternotomy, followed by an infusion of 0.5 Mio KIU/h until the end of surgery; 2 Mio KIU added to the priming volume additionally). Graft patency was evaluated by angiography in 44 aprotinin and 35 placebo patients between the 18th and 35th days postoperatively. There was no difference in the overall graft occlusion: in the aprotinin group 89.5% (111/124) grafts were found patent compared to 87.2% (89/102) in the placebo group. Of the aprotinin patients 72.7% (32/44) and 71.4% (25/35) of the placebo patients had all grafts patent. Venous grafts were occluded in 16% (7/44) of aprotinin patients and in 29% (10/35) of placebo patients. On the other hand 5/27 patients in the aprotinin group vs 0/27 in the placebo group had occluded internal mammary artery (IMA) grafts (P = 0.0511%). Graft occlusions were not accompanied by signs of myocardial infarction in any case. Fifty-one patients in the aprotinin group and 47 patients in the placebo group were valid for parameters of clinical efficacy: blood loss within 6 h postoperatively was reduced by 58.5% in the aprotinin group (P < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)


The Annals of Thoracic Surgery | 2010

Complex Surgical Valve Repair After Failed Percutaneous Mitral Intervention Using the MitraClip Device

Stephan Geidel; Jörg Ostermeyer; Michael Lass; Michael Schmoeckel

Catheter-based techniques of percutaneous valve intervention are recently being performed in an increasing number of patients. We finally report a case of successful, but complex surgical mitral valve repair 32 days after failed percutaneous intervention with severely aggravated mitral pathology caused by the catheter-based procedure. It is outlined that the conditions for surgery can be severely deteriorated, thereby reducing the chance for successful surgical repair after preceding mitral intervention.


Interactive Cardiovascular and Thoracic Surgery | 2008

A 5-year clinical experience with bipolar radiofrequency ablation for permanent atrial fibrillation concomitant to coronary artery bypass grafting and aortic valve surgery

Stephan Geidel; Michael Lass; Jörg Ostermeyer

This study analyses the 5-year results of permanent atrial fibrillation (pAF) bipolar radiofrequency (RF) ablation surgery concomitant to coronary artery bypass grafting (CABG) and/or aortic valve (AV) surgery. Eighty-five patients with pAF (0.5-30 years) underwent bipolar RF ablation procedure concomitant to CABG/AV surgery. All patients were restudied to assess survival, conversion rate to stable sinus rhythm (SR) and New York Heart Association (NYHA) class at 8+/-1 days and at 3+/-1 and 32+/-15 months after surgery. Survival at time of re-examination was 100%, 98% and 96%, respectively (three non-cardiac deaths), SR could be documented in 61%, 74% and 78% of patients. Long-term AF before surgery and larger size of the left atrium (LA) were predictive for postoperative AF return (P=0.005, P=0.03); 88% of patients with small preoperative LA-size (<50 mm) and 85% with pAF-duration time <5 years had stable SR at late follow-up. Cardiac rhythm at three months was predictive for long-term rhythm-prognosis (P<0.0001). NYHA-class improved significantly after surgery (P<0.0005), particularly when SR was achieved (P=0.046). Permanent AF bipolar RF ablation surgery revealed excellent results in AV/CABG patients. It could be demonstrated that established SR remained stable over time. Preoperative pAF-duration time and LA-size are useful variables to predict the success rate of ablation.


The Journal of Thoracic and Cardiovascular Surgery | 2011

Ablation surgery in patients with persistent atrial fibrillation: an 8-year clinical experience.

Stephan Geidel; Korff Krause; Sigrid Boczor; Karl-Heinz Kuck; Michael Lass; Jörg Ostermeyer; Michael Schmoeckel

OBJECTIVE This analysis was undertaken to evaluate the results of persistent atrial fibrillation ablation procedures concomitant to open surgery and to identify risk factors for persistent atrial fibrillation recurrence. METHODS Since 2001, a total of 325 consecutive patients with persistent atrial fibrillation (duration, 0.5-33 years) have undergone persistent atrial fibrillation ablation concomitant to open surgery by creating 2 encircling isolation lesions around the left and right pulmonary veins and a connecting lesion between both with the use of radiofrequency ablation procedures. Patients were restudied at discharge, 3 months, and 3 years after surgery. RESULTS Survivals at the time of reexamination at discharge, 3 months, and 3 years were 97.8%, 96.2%, and 94.4%, respectively. Stable sinus rhythm could be documented in 72.1%, 73.9%, and 75.6% of surviving patients, respectively. Long-term persistent atrial fibrillation before surgery and a larger left atrium were predictive of postoperative persistent atrial fibrillation return (P<.001). Statistical analysis demonstrated cutoff points of 5 years for persistent atrial fibrillation and 55 mm for left atrium diameter; 89.7% of patients with persistent atrial fibrillation duration of less than 5 years and 84.5% of patients with left atrium size of 55 mm or less were in stable sinus rhythm at late follow-up. Cardiac rhythm at discharge and at 3 months was predictive of long-term rhythm prognosis (P<.001). Age, gender, concomitant diseases (eg, arterial hypertension, diabetes, renal insufficiency, or pulmonary disease), and the underlying cause of heart disease did not significantly influence the postoperative cardiac rhythm. CONCLUSIONS The duration of persistent atrial fibrillation and the size of the left atrium are the most reliable preoperative variables to predict the success rate of ablation concomitant to open surgery. The probability of reestablishing stable sinus rhythm is excellent when persistent atrial fibrillation duration is short and left atrium size is small.


Heart Surgery Forum | 2008

Seven-Year Experience with Ablation of Permanent Atrial Fibrillation Concomitant to Mitral Valve Surgery in 152 Patients

Stephan Geidel; Michael Lass; Jörg Ostermeyer

BACKGROUND This study analyzed 7 years of results for monopolar endocardial radiofrequency (RF) ablation of permanent atrial fibrillation (pAF) concomitant to mitral valve (MV) surgery. METHODS Between 2001 and 2007, 152 patients who had experienced pAF for a median of 4.0 years (interquartile range, 1.5-8.0 years; range, 0.5-33 years) underwent monopolar endocardial RF ablation procedures (pulmonary vein isolation plus a connecting lesion) concomitant to MV surgery. All patients were reexamined to assess survival, conversion rate to stable sinus rhythm (SR), and New York Heart Association (NYHA) class at 8 +/- 1 days after surgery and follow-ups at 3 +/- 1 months and 41 +/- 24 months postoperatively. Data were analyzed exploratatively. RESULTS The survival rates at the 3 reexamination times were 97%, 95%, and 92%, respectively (6 cardiac and 6 noncardiac deaths), and the corresponding SR rates were 74%, 75%, and 73%. The NYHA class of the patients improved significantly after surgery (P = .006), particularly when a stable SR had been achieved (P = .039). Long-term pAF prior to surgery and a larger left atrium (LA) preoperatively were predictive of the return of postoperative AF (P = .0002, and P = .0003, respectively). Ninety-one percent of the patients with a preoperative pAF duration of <5 years and 88% of the patients with an LA size of <or=55 mm were in stable SR at the late follow-up. The cardiac rhythm at discharge and 3 months after surgery were predictive of a prognosis of long-term rhythm (P = .021, and P = .00002, respectively). Age, sex, and the underlying etiology of MV disease did not have a significant influence on postoperative cardiac rhythm. CONCLUSION This study demonstrated that a SR established after combined pAF ablation and MV surgery remains stable over time. Preoperative LA size and pAF duration are useful parameters for evaluating the success rate of pAF ablation concomitant to MV surgery.


Heart Surgery Forum | 2008

Restrictive Mitral Valve Annuloplasty for Chronic Ischemic Mitral Regurgitation: A 5-Year Clinical Experience with the Physio Ring

Stephan Geidel; Michael Lass; Jörg Ostermeyer

BACKGROUND This study investigated the results of restrictive mitral annuloplasty with the semirigid Carpentier-Edwards Physio ring in patients with moderately severe to severe chronic ischemic mitral regurgitation (IMR) and advanced ischemic cardiomyopathy (ICM). METHODS From 2003 to 2007, 100 consecutive patients (mean age +/- SD, 69 +/- 10 years) with chronic IMR of grades 3 to 4 (3.6 +/- 0.5) and a left ventricular ejection fraction (LVEF) of 31% +/- 9% (range, 12%-45%) underwent standardized restrictive prosthetic ring annuloplasty (ie, downsizing of 2.7 +/- 1.0 [range, 2-4] ring sizes) and concomitant coronary artery bypass grafting. All surviving patients were restudied 8 +/- 1 days, 3 +/- 1 months, and 2.5 +/- 1.0 years after surgery to assess survival, residual MR, New York Heart Association (NYHA) class, and LV function (end-systolic and end-diastolic dimension/volume indices and LVEF). Data were analyzed exploratatively. RESULTS Survival rates at the postoperative reexamination times were 98%, 97%, and 94%, respectively (1 noncardiac and 5 cardiac deaths). NYHA class improved from 3.5 +/- 0.5 to 1.4 +/- 0.5 (P < .0005). The residual MR grades at discharge, early follow-up, and late follow-up were 0.4 +/- 0.5, 0.5 +/- 0.5, and 0.4 +/- 0.6, respectively (P < .0005). Post-operative recurrence of significant IMR (>grade 2) was absent in all patients. The leaflet coaptation height was 8 +/- 1 mm and did not decrease significantly over time. All LV dimension and volume indices and the LVEF (41% +/- 9% at 2.5 years) improved significantly after surgery (P < .0005), even in patients with initially severely reduced myocardial function and a preoperative LVEF of <30% (n = 42; LVEF, 22% +/- 5% versus 33% +/- 6% at late follow-up; P < .0005). CONCLUSION Restrictive mitral valve annuloplasty using the semirigid Physio ring corrected chronic IMR in ICM patients with very low mortality and improved contractility. Surgery also prevented recurrence of significant IMR in parallel with the phenomenon of postoperative continuous reverse myocardial remodeling.


European Journal of Cardio-Thoracic Surgery | 2005

Downsizing of the mitral valve and coronary revascularization in severe ischemic mitral regurgitation results in reverse left ventricular and left atrial remodeling

Stephan Geidel; Michael Lass; Carsten Schneider; Gaby Groth; Sigrid Boczor; Karl-Heinz Kuck; Jörg Ostermeyer


European Journal of Cardio-Thoracic Surgery | 2005

Three years experience with monopolar and bipolar radiofrequency ablation surgery in patients with permanent atrial fibrillation

Stephan Geidel; Jörg Ostermeyer; Michael Lass; Matthias Betzold; Anh Duong; Folke Jensen; Sigrid Boczor; Karl-Heinz Kuck


European Journal of Cardio-Thoracic Surgery | 1995

Aprotinin in elective primary bypass surgery

Michael Lass; Adam Welz; Mathias Kochs; Gabrielle Mayer; Melanie L. Schwandt; Andreas Hannekum


Indian pacing and electrophysiology journal | 2005

Permanent atrial fibrillation ablation surgery in patients with advanced age

Stephan Geidel; Michael Lass; Jörg Ostermeyer

Collaboration


Dive into the Michael Lass's collaboration.

Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Top Co-Authors

Avatar
Researchain Logo
Decentralizing Knowledge